	function getCookie(c_name){
		/*console.log(document.cookie)*/
		if (document.cookie.length>0){ 
			c_start=document.cookie.indexOf(c_name + "=");
			if (c_start!=-1){ 
				c_start=c_start + c_name.length+1 
				c_end=document.cookie.indexOf(";",c_start)
				if (c_end==-1) c_end=document.cookie.length
				return unescape(document.cookie.substring(c_start,c_end))
			} 
		}
		return ""
		
	}
		//设置COOKIE
		function setCookie(c_name,value,expiredays){
			var exdate=new Date()
			exdate.setDate(exdate.getDate()+expiredays)
			document.cookie=c_name+ "=" +escape(value)+
			((expiredays==null) ? "" : "; expires="+exdate.toGMTString())+";path=/"
		}
		//if语句
		function checkCookie(){
			username=getCookie('username')
			if (username!=null && username!=""){
				alert('Welcome again '+username+'!')
			}
			else {
		  		username=prompt('Please enter your name:',"")
		  		if (username!=null && username!=""){
		    		setCookie('username',username,365)
		    	}
		 	}
		}
		
		function removeCookie(key){//清除cookie=============================
		  setCookie(key,getCookie(key),-1);
		}